When a user changes their Google password, it revokes access to all applications.
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"Automatic OAuth 2.0 token revocation upon password change
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To increase account security for Google users, OAuth 2.0 tokens issued for access to certain products are automatically revoked when a user's password is changed. Third-party mail apps like Apple Mail and Mozilla Thunderbird―as well as other applications that use mail scopes to access a user’s mail―will stop syncing data upon password reset until a new OAuth 2.0 token has been granted. A new token will be granted when the user re-authenticates with their Google account username and password.

Third-party mail applications on mobile are also included in this policy change. For example, users who use the native mail application on iOS will now have to re-authenticate with their Google account credentials when their password has been changed. This new behavior for third-party mail apps on mobile aligns with the current behavior with Gmail on iOS and Android, which also require re-authentication upon password reset.

The token revocation process does not include applications built on Apps Script, even if the script accesses mail.

Notes:

• If the password change is triggered from an Android device, the OAuth token for the account sync used by this Android device is not revoked.

• Gmail IMAP sessions authenticated using OAuth aren't affected by a password change, but are limited to the validity period of the access token (usually 1 hour)."
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To read more, visit Google's WorkSpace Admin Help Page.